A prior art face grinder assembly is generally indicated by the numeral 10 in FIG. 1. The prior art face grinder assembly 10 includes a grinding stone 20, and is used in conjunction with a tire uniformity machine 12 to remove irregularities from a tire T. The prior art face grinder assembly 10 includes a face grinder frame having two forks 22 which are attached to a bracket 23 which is mounted on the frame 14 of the tire uniformity machine 12. The forks 22 are spaced apart to accommodate a sub-assembly 24 that carries the grinding stone 20. The sub-assembly 24 includes a pivot bracket 26, which is pivotably attached between the forks 22 as by a pin 25, and includes cylindrical rails 32 supporting a carriage 33 therebetween. The carriage 33 supports a grinder head 38 which carries the grinding stone 20.
During operation of the prior art face grinder assembly 10, the sub-assembly 24 is alternately reconfigured between an upwardly inclined retracted position and a horizontally extended position. To provide the horizontally extended position, a first piston 42 is used to extend the cylindrical rails 32 and carriage 33 relative to the forks 22 such that the grinder head 38 is positioned adjacent the tire T in position P1. When located in position P1, the grinder head 38 is capable of removing the above-discussed irregularities from the tire T.
To provide the upwardly inclined retracted position, a second piston 48 is used to pivot the cylindrical rails 32 and carriage 33. In this upwardly inclined retracted position, the cylindrical rails 32 and carriage are inclined upwardly relative to a conveyer 16 by the second piston 48, and are ideally retracted relative to the forks 22 by the first piston 42.
In the upwardly inclined retracted position, a tire T is normally capable of passing underneath the sub-assembly 24 along the conveyer 16. Normally, there is clearance for a tire T to pass under the pivot bracket 26 and grinder head 38. However, tires T having larger widths are increasingly being checked for uniformity. To grind tires T having larger widths, a larger grinding stone 20 is utilized. As seen in FIG. 1, when a large width tire T is tested in the tire uniformity machine 12 having the prior art face grinder assembly 10, the tire T at position P2 will likely not pass under the grinder head 38 (even in the upwardly inclined retracted position) and at position P2′ definitely will not pass under the pivot bracket 26.
One attempt at accommodating tires having larger widths has been made. This design operates on the same principle as prior art face grinder assembly 10. However, this design includes a new pivot point located farther from the tire uniformity machine 12. That is, the forks 22 are lengthened, and a new sub-assembly is pivotably attached (using a pivot bracket) between the forks 22 farther from the tire uniformity machine 12. The new sub-assembly includes lengthened cylindrical rails 32 and a lengthened carriage 33 to account for the increased distance from the pivot point to the tire uniformity machine 60.
By repositioning the pivot point, and providing a new sub-assembly with lengthened cylindrical rails and a lengthened carriage, the grinder head thereof may be raised to a greater extent relative to the conveyer 16. As such, tires T having larger widths can pass under the grinder head. Unfortunately, these tires T may still not pass under the pivot bracket, and the increased length of the forks 22 causes this design to occupy space normally used for further downstream processing of the tire T. Furthermore, the design increases the “footprint” of the tire uniformity machine 12, and requires the conveyer 16 to also be lengthened. When processing thousands of tires per day, space is at a premium, and the additional distance that a tire T must travel along the conveyer 16 adds to the processing time. Moreover, this design requires a new sub-assembly (with lengthened cylindrical rails and carriage). Consequently, the sub-assembly 24 cannot be retrofitted to existing tire uniformity machines, thereby adding expense and machine downtime.
Therefore, there is a need to provide an improved face grinder assembly capable of allowing a tire T with a large width to pass thereunder.